A multifunction machine, piece of equipment, building, or room is designed to have several different uses, not only one. The classic picture is a multifunction printer: it prints, copies, scans, and sometimes sends a fax, all in one box. A multifunction hall might hold a meeting in the morning and a class at night.

The word is at home on product boxes and in building plans. It often sits in front of a noun: a multifunction device, a multifunction display in a car. You will also hear multifunctional, which is the same idea with a longer adjective shape. Both are fine; shops like the shorter multifunction on a label.

As a noun on its own, multifunction is less common in everyday talk — people name the thing (“the printer”) more than they name “a multifunction.” The sense you need is the designed-for-several-uses one. It does not mean “this thing works” (that is function as a verb). It means “this thing was built to do more than one job.”